一种基于环上LWE的广义签密方案

A Generalized Signcryption Scheme Based on LWE over Rings

广义签密可以灵活地工作在签密、签名和加密三种模式,具有很强的实用性.本文结合基于格的签名方案和密钥交换协议,构造了一个无陷门的广义签密方案.方案构造中引入了区分函数,根据输入的发送方与接收方密钥情况来自动识别加密、签名和签密三种模式,保障了算法在这三种工作模式下的优美对称性.基于环上判定性LWE问题,并借鉴FO13的方法,证明了该方案满足自适用抗选择密文攻击不可区分性安全性(IND-CCA2)和自适用抗选择消息攻击强不可伪造性安全性(SUF-CMA).该方案是基于Fiat-Shamir的中止(abort)框架,没有用到复杂的原像抽样和陷门生成算法,具有较高的计算效率.

Generalized signcryption can run flexibly in three modes:signcryption,signature and encryption,and has strong practicability.This paper combines lattice⁃based signature scheme and key exchange protocol to construct a trapdoorfree generalized signcryption scheme.In the construction,a distinguishing function is introduced,which automatically identi⁃fies the three modes of encryption,signature and signcryption according to the key conditions of the sender and the receiver.This ensures the excellent symmetry of the algorithm in these three modes.Finally,based on the deterministic learning with errors(LWE)problem on the ring,itused the method of FO13 toprove that the scheme satisfies the indistinguishability against adaptive chosen ciphertext attack(IND-CCA2)security and the strong unforgeability against choosing message at⁃tack(SUF-CMA)security.It is based on Fiat-Shamir with abort framework which does not use complex preimage sample al⁃gorithmand trapdoor generation algorithm,so it has high computational efficiency.